[unreadable] Coronary artery disease (CAD) is the leading cause of death in Western civilization. The 747,000 individuals per year who receive an implantable pacemaker represent a population who are at high-risk for myocardial infarction. While these patients have a sophisticated system to acquire and process the intracardiac ECG, current generation pacemakers do not sense myocardial ischemia or emerging infarctions. This motivated our Phase I study on the effect of myocardial ischemia on the intracardiac ECG. We have developed a novel transvenous lead-based electrode configuration and Time Frequency Window Index (TFWI) algorithm to demonstrate the potential for a pacemaker to detect emerging infarctions. These ideas were validated in a porcine model of myocardial infarction. We now propose to extend our studies to investigate the effect of transient ischemia and graded stenoses on the intracardiac ECG. Our central hypothesis is that the ECG sensed by a transvenous lead will demonstrate changes which are correlated with the extent and time course of ischemia. We will test this hypothesis and then use the results to further develop filtering and adaptive thresholding strategies to discriminate emerging infarctions from episodes of transient ischemia. In summary, we hope to develop a more thorough understanding of the effects of ischemic burden on the intracardiac ECG. It is our long-term goal to develop this into a reliable sensor for emerging myocardial infarctions. Such technology could be tied to "patient-alert" features, which are common in today's implantable cardiac devices, to minimize time-to-treatment and thus mortality. [unreadable] [unreadable]